How do i test this schematics?

eetech00

Joined Jun 8, 2013
4,004
so would i have to test parts of the schematics separately?
Declare what the circuit is supposed to do (its purpose).
Divide the circuit into "functional blocks" (this looks like its already been done).
Then, develop test cases for testing each of the functional blocks.
The test cases define what to test and the expected results.
 

BobTPH

Joined Jun 5, 2013
9,138
No idea what your circuit us, but, just ss an example, here is how you would test an audio amplifier in the simulator:

1. Create an AC voltage source that is a sine wave at 1KHz and connect it to the input of the amp.

2. Run transient analysis.

3. Probe the inout and output to see the waveforms.

To test frequency response:

1. Set up an AC analysis as a frequency sweep across the audio spectrum plus some more.

2. Make your input voltage source the AC analysis source.

3. Run the AC analysis.

4. Probe the output. You will get a Bode diagram.

To test for distortion:

Run a Fourier analysis. Look at the error log, it will give you the total harmonic distortion.

You might want to find a tutorial that covers these topics as LTSPICE is not all that intuitive.
 

atferrari

Joined Jan 6, 2004
4,783
No idea what your circuit us, but, just ss an example, here is how you would test an audio amplifier in the simulator:

1. Create an AC voltage source that is a sine wave at 1KHz and connect it to the input of the amp.

2. Run transient analysis.

3. Probe the inout and output to see the waveforms.

To test frequency response:

1. Set up an AC analysis as a frequency sweep across the audio spectrum plus some more.

2. Make your input voltage source the AC analysis source.

3. Run the AC analysis.

4. Probe the output. You will get a Bode diagram.

To test for distortion:

Run a Fourier analysis. Look at the error log, it will give you the total harmonic distortion.

You might want to find a tutorial that covers these topics as LTSPICE is not all that intuitive.
There are some LTSpice tutorials in the web by Simon Bramble. Not sure but maybe they could help.
 

Thread Starter

tienk

Joined Apr 8, 2024
76
Declare what the circuit is supposed to do (its purpose).
Divide the circuit into "functional blocks" (this looks like its already been done).
Then, develop test cases for testing each of the functional blocks.
The test cases define what to test and the expected results.
the circuit is brake system plausibility device where if a driver brakes and accelerates at the same time for 500ms it shuts down the engine, so it has 2 sensor inputs, each sensor is connected to a window comparator to
Declare what the circuit is supposed to do (its purpose).
Divide the circuit into "functional blocks" (this looks like its already been done).
Then, develop test cases for testing each of the functional blocks.
The test cases define what to test and the expected results.
so for example how would i test the window comparators on the left which is supposed to keep the input of a current sensor between the range set by the voltage dividers which in this case is 1.6-4.5V but if the input were to go above or below that range then it would output low here is what it should look like
1713473404060.png
 

crutschow

Joined Mar 14, 2008
34,682
how exactly am i supposed to know them
Exactly from the application.
You have stated:
"the circuit is brake system plausibility device where if a driver brakes and accelerates at the same time for 500ms it shuts down the engine,"
So you should be able to infer the inputs and the expected outputs for that.
If you don't know them, then you need more information about the requirements of the system, which we certainly don't know.
 

Thread Starter

tienk

Joined Apr 8, 2024
76
Exactly from the application.
You have stated:
"the circuit is brake system plausibility device where if a driver brakes and accelerates at the same time for 500ms it shuts down the engine,"
So you should be able to infer the inputs and the expected outputs for that.
If you don't know them, then you need more information about the requirements of the system, which we certainly don't know.
if you mean like the input voltages for example and
Exactly from the application.
You have stated:
"the circuit is brake system plausibility device where if a driver brakes and accelerates at the same time for 500ms it shuts down the engine,"
So you should be able to infer the inputs and the expected outputs for that.
If you don't know them, then you need more information about the requirements of the system, which we certainly don't know.
do you mean like the voltage inputs for example and its output, if so yes
 
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